The meaning of that word has grown on me a lot lately. I've always liked it.
But sometimes leaving something at the forefront of your mind for a little longer than you usually do, helps you appreciate the true meaning.
It can be interpreted as the physical act of exploring new areas, which could be because you're looking for new spots but it might as well be out of plain curiosity.
An opinion that might be considered old-fashioned (in the parkour-world that is) is to regard exploration as an essential fragment of what it takes to be able to 'live' the pk-way.
A different way to look at it is to link exploration with creativity and being 'allround'.
If the latter doesn't make sense yet try to look at it this way.
An athlete is considered allround, if he/she often has explored (successfully) the different branches one can take when trying to master a skill-tree.
Most athletes will focus on certain aspects (the classic parkour vs freerunning example), some will specialize in specific subbranches (descents, flip precisions...).
This focus is completely natural and can be linked to someone's style and interest, determined to some extent by the current trend in the parkour culture.
However, I do see the complete ignoration of what is not your specialty as detrimental to one's (movement) development.
When it comes to creativity the exploration part is essential. As I've stated before, creativity is not necessarily about doing something that other people don't do, it's more on an individual level, about doing something that you're not used to doing. Exploring the different ways your body can interact with the environment is what parkour is all about. It's not about being able to perform a 10ft standing pre between two perfectly parallel walls, or a massive standing arm jump.
These do show, once again to a certain extent, the physical level you're at, but rarely reveal anything about your mental level.
This is why we've got to be so careful with all the pk-parks popping up all over the place.
I'm not against them, I do think they help an athlete to improve his overall level. But there has to be room for exploration. Some awkward edges, rails that don't seem to useable at all, non-grippy surfaces... should be a must in every new park built.
A second thing to be aware of is that this idea of exploration is present in a lot of us... a lot of us who train or have been training parkour.
People who haven't trained for a couple of years probably won't feel the same way about it.
That's why we will always need community people at the forefront of the leading governing organizations.
Parkour can only be developed properly with the help of the community. A big company organizing events, competitions will always feel the need to try and define what parkour is.
The truth is that this exploration-aspect of the sport will never allow for a confined definition.